Means for fighting fire in at least one cable or line run

ABSTRACT

A device for fighting fires in at least one cable or line run At least one pipe, which contains a fire-extinguishing agent under positive pressure, is laid in at least one cable or line run. The wall of this pipe is produced from a material whose melting point is chosen to be lower than the ignition point of the cable sheath of an adjacent cable.

BACKGROUND OF THE INVENTION

The invention relates to a means or device for fighting fire in at leastone cable or line run containing a cable and/or a line, at least onepipe, which contains a fire-extinguishing agent under positive pressureand is laid continuously in the cable or line run, and the wall of thispipe is produced from a material whose melting point is chosen to beequal to or lower than the ignition point of the cable sheath or theline.

A means of this type is disclosed by DE-A1-27 45 370.

The brochure from Walther & Cie. AG on "Spruhflutanlagen furTransformatoren und Kabelkanale" [Spray flooding systems fortransformers and cable ducts] 3/72 discloses an extinguishing device inwhich a pipe which has a large number of extinguishing nozzles is laidin a cable duct. In the event of fire, a liquid extinguishing agent isforced into the pipe from a central control point and is thus sprayedout by the spray nozzles. Since the entire system, or at least in eachcase a relatively large part thereof, is placed under pressure, theextinguishing agent emerges within the entire system, or within arelatively large part thereof, and the cable duct is flooded.

EP-A2 0 077 679 discloses a fire-protection system in which a cable ducthas a large number of small flexible containers having coverings madefrom a crosslinked polymer material. These small containers contain anonflammable liquid, in particular water. The coverings are constructedsomewhat like a cushion and are arranged one behind the other. If a firebreaks out, then the heat produced is to a certain extent absorbed bythe evaporation of the liquid in the interior of the small containers,without the latter bursting. In this way, since heat is drawn off, theaction of the heat may last longer. If the heat rises further, then thecovering of some of the small containers tears apart, and the evaporatedliquid flows out. The small containers are expediently only partlyfilled with the liquid, so that they can expand to a greater extent.However, the production of such small containers that are filled with aliquid and lined up in a row is extremely complicated.

DE-A1 33 37 532 discloses an extinguishing device having a containerwhich is intended to accommodate an extinguishing agent that is underpressure, and to which there is connected a piece of pipe which, in theregion of its end, is closed by a wall. This wall consists of a materialwhich dissolves or liquefies when a predetermined temperature isexceeded.

U.S. Pat. No. 5,276,433 discloses a temperature sensor which isincorporated, for example, in the outlet of a ventilation system. Itcontains a pipe which consists of plastic and is filled with a liquidunder pressure. When this pipe is subjected to a high temperature, theliquid in the interior of the pipe begins to boil and the pipe bursts,the pressure drop which is produced, is used to close the ventilatorflaps.

GB-A 1 357 010 discloses a fire-extinguishing device which is intendedto be incorporated in a housing that is exposed to the risk of fire. Itis possible for the housing to contain, for example, a televisionreceiver, a computer, a photocopier, an office machine or a motor. Laidin the housing is a pipe which contains a liquid fire-extinguishingagent under pressure. In the event of fire, the pipe becomes soft,bursts and the liquid flows out.

In the case of a means for fighting fires, which means has at least onepipe which contains a fire-extinguishing agent under pressure and thewall is of a material with a melting point that is equal to or less thanthe ignition point of the cable sheath or line. The extinguishing agentmust be kept in the pipes for a long period of time. During these longstanding times, the extinguishing agent may undergo changes.

SUMMARY OF THE INVENTION

The invention is therefore based on the object of indicating a way inwhich such changes can be avoided to the greatest possible extent, andthus the service life of the extinguishing-agent system can be improved.

In the case of a means for fighting fire according to the invention,this object is achieved in that the pipe is equipped with a water vaporbarrier.

As a result of the pipe which contains the extinguishing agent beingequipped with a water vapor barrier, the diffusion of water or watervapor through the pipe wall is prevented, so that the service life ofthe extinguishing agent can be kept very long. In the case ofhygroscopic extinguishing agents, the water vapor barrier has theadvantage that it is less easily possible for clumping to occur, sincemoisture that is present on the outside (for example moisture in theair) cannot pass to the inside to the fire-extinguishing agent. If aliquid extinguishing agent is used, there is an advantage insofar asthis cannot emerge to the outside from the pipe interior, so that lossesof fire-extinguishing agents can be avoided to the greatest possible itis also possible in this way, for extinguishing agents under pressure,for the operating pressure to be better maintained as well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of a building that isprovided with a fire-protection means according to the invention,

FIG. 2 is a plan view of an embodiment of how a pipe can be fitted abovethe cables in a cable duct and

FIGS. 3 to 5 are cross sectional views of three embodiments of pipeswhich are provided with signal conductors and, if appropriate, with awater vapor barrier and are intended for carrying the extinguishingagent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a building BD, that has three rooms RM1, RM2, RM3that are located one above another. At least one cable, which may beconstructed as 15 a telecommunications cable and/or as a power supplycable, enters this building via the foundation FM. In the presentexample, it is assumed that three cables CA1-CA3 are fed in. In general,these cables, which generally come in underground, are fed todistributors and from there are led on further via distribution orbranching cables. In the present example, these distributors have beenleft out in order to give a clearer illustration, and the cables aredepicted schematically as being fed directly to the individual rooms. Inthe building itself, vertically running cable ducts CS11 and CS21 (oneither side of the room RM1), CS12 and CS22 (on either side of the roomRM2) and CS13 and CS23 (on either side of the room RM3) are illustratedas cable or line runs. These vertically running cable ducts are usuallycovered over with respect to the interior of the room by a wall, liningor the like and constitute a chimney-like structure which, in the eventof a fire, passes on the fire particularly quickly.

In the present example, it is assumed that the cables CA1-CA3 are laidas ring lines, that is to say are also led wholly or partially over therespective ceilings, to the opposite side, or to a different side, ofthe room, for example on cable trays or cable racks. The cables thus runhorizontally underneath the ceiling, in the so called plenum, in a cableor line run, which is designated in each case by PL1 for room RM1, PL2for room RM2 and PL3 for room RM3.

In the event of a short circuit within the cable system, or in the eventof overheating or the outbreak of fire in one of the rooms, there is therisk that one or all of the cables CA1-CA3 will catch fire and, becauseof the wide distribution of the cable ducts CS11-CS21 and/or of theceiling ducts PL1-PL3, a rapid spread of fire will take place. This isremedied in that, in the respective cable ducts CS11-CS21, at least onepipe with a fire-extinguishing agent is laid over, between or under thecables (that is to say as close as possible and, as far as possible,also in physical contact). The pipe material has a lower melting pointthan the ignition point of the sheathing materials or the temperature atwhich the cable sheath begins to burn for the cables CA1-CA3. If thesecable sheaths have different ignition points (for example because theyconsist of different materials), then the melting point of the rawmaterial carrying the extinguishing agent is advantageously to be chosensuch that said raw material malts at the ignition point of the cablesheath with the lowest ignition point. This pipe, filled withextinguishing agent, should be under pressure, which in the presentexample is realized in a simple manner by a storage container CT beinginstalled on the roof of the building BD and being filled with anextinguishing agent FM, which is preferably a liquid. Connected to thiscontainer CT is a pipe RO, which, in the present example, divides intotwo pipes RO1 and RO2 after passing through the uppermost buildingceiling DE3. These pipes RO1 and RO2 are advantageously extendingthrough all the cable ducts CS1l to CS21 and expediently also throughthe horizontally running ceiling ducts PL1 to PL3, and now in thevicinity of the cables. In the present example, it in assumed that thetwo pipe systems RO1 and RO2 are also connected to each other as ringlines, that is to say the pipes RO22 and RO12 running in theintermediate ceilings each connect the vertically running pipe stringsRO1 and RO2 to each other. This has, for example, the advantage that,with a given pipe cross section, virtually twice the amount ofextinguishing agent can emerge at the respective point of a fire if thelatter is located in the ceiling region. The fire-fighting means canalso be modified in such a way that a plurality of storage containersare provided in a building, in particular at different heights (forexample in each story, and are then advantageously assigned separatepipe systems.

Because of the relatively low melting point of the pipe wall of the pipesystem, in the event of a fire breaking out the respective pipe willmelt, burst or break open precisely at the point where the flame occursand, as a result, clears the path for the extinguishing agent FM to flowout. As a result of the relatively high pressure of the extinguishingagent, the latter is sprayed out over a relatively large area, and thesource of the fire is thus quickly and reliably extinguished in thisway.

Suitable extinguishing agents are fire-extinguishing liquids (forexample water), gases (for example nitrogen) and also pulverulentextinguishing agents, such as the extinguishing agents used in the knownhand-operated fire extinguishers. Furthermore, it is also possible toprovide an extinguishing foam or agent, or its basic substances, in theinterior of the pipe. This foam then emerges at the point of the fire tospecifically fight and extinguish the fire locally. Foam extinguishingagent of this type in some cases have the added advantage that, once thefire has been extinguished, the fire-extinguishing agent also ceases toemerge.

The installation of the cable systems within the building or the plantcan be modified in many ways and is not restricted to the schematicdistribution structure illustrated in FIG. 1. For example, it ispossible to provide just one vertical cable or line run CS11 to CS13,from which the cables are distributed over the room in the manner ofspur lines, for example via the ceiling distribution systems PL1-PL3,while dispensing with a left-hand cable or line run corresponding toCS21 to CS23. Furthermore, it is possible, in addition to or elseinstead of ceiling distribution systems, for the cables to be providedin the floors of the respective rooms. Equally, it is also possible toprotect cable or line systems in mobile areas, such as in vehicles (forexample underground trains), the vehicle corresponding, for example, toone of the illustrated rooms. It is also possible for lines, such ascontrol lines, to be laid instead of or together with the cables. Inthis case, the melting point of the pipe carrying the extinguishingagent should be based on the ignition point of the insulation of thelines, that is to say should be chosen to be equal to or lower than thelatter.

The pressure in the pipeline system RO1 and RO2 can also be produced ina manner other than hydrostatically. For example appropriate pressurecontainers and pressure pumps can be provided and these will take overor control the necessary additional delivery of the extinguishing agentas required when a pressure drop resulting from a fire with emergence ofextinguishing agent occurs.

FIG. 2 shows that, in particular in the case of cable ducts having alarge number of cables, it is expedient if, rather than being guidedrectilinearly and essentially parallel to the individual cables CA1 toCAn, the pipe ROW carrying the extinguishing agent is guided in aserpentine fashion and preferably over the entire width of the bundle ofcables, by which means the space area filled by the cables CA1 to CAncan be covered better. It is also possible for the pipe ROW with theextinguishing liquid under pressure to be wound around the bundle ofcables CA1 to CAn in the manner of a helical coil, and an a result forparticularly good monitoring and a reliable extinguishing function to beachieved. Close physical contact between the pipe ROW and the cables CA1to CAn to be protected is expedient.

FIG. 3 illustrates is a cross section through a fire-protection pipeRO31 in the sense of the invention. The wall of this pipe RO31expediently consists of plastic material, it being advantageouslypossible to use polyethylene in particular, since its melting point islower than that of most PVC-sheathed cables used hitherto. Even when thelaid cables are sheathed with polyethylene, the pipe RO31 is destroyedin the event of a fire as a result of its lower melting point, and theextinguishing agent contained therein emerges. This process can beaccelerated further if a polyethylene with a particularly low meltingpoint is used for the pipe RO31. In order to prevent moisture frompermeating into the pipe, it is advantageous, when hygroscopicextinguishing agents are used to provide the pipe on the inside with avery thin-walled water vapor barrier WB, for example made of aluminumand/or plastic film. This water vapor barrier can also be applied to theoutside or embedded in the wall of the pipe RO31.

It is expediently possible for monitoring devices, for example in theform of electric conductors EL31 and EL32 or dielectric conductors, tobe connected to the pipe. In the cross-sectional illustration of FIG. 3,these are embedded in the wall material (for example on opposite sidesof the pipe RO31), and can advantageously be used for signaling or forcontrol. The electric conductors can also be embedded in the pipe wallso that they run helically.

In FIG. 4, two, preferably twisted together, electric conductors EL41and EL42 are accommodated in a small pipe SR4 that is connected to thepipe RO41 via a web ST4. In FIG. 5, four conductors EL51 to EL54 of thistype are provided. It is also possible to construct or use theconductors EL51 to EL54 as a telecommunications cable. Electricshielding of the conductors can also expediently be provided, forexample by means of a thin metal foil.

In the event of a fire breaking out, there is a change in the pressurewithin the extinguishing-line system. This pressure change can be usedin an alarm device AE, by means of a sensor (designated by SF in FIG. 1)assigned to the extinguishing system, for example in the form of asignal generator, a manometer or the like, to trigger a fire alarm or toreport to a fire station.

It is also possible for the change in electrical properties, for exampleof the insulation resistance between conductors assigned to the pipes,to be determined and, as indicated by SE in FIG. 1, to be forwarded tothe alarm device AE.

The response of a sensor (for example signal generator and/or pressuremanometer) can be forwarded to the alarm device, for example AE, via theconductors EL31 and EL32 or EL41, EL42 or EL51 to EL52. In the event ofuse in large systems, it is possible for two further conductors EL53 andEL54 (see FIG. 5) to be provided, and these, in particular, also permitthe remote feeding of active electronic sensors. In the event of usingrapid, digital systems, the 2 or 4 conductors can be twisted andprovided with a shield, which prevents the alarm signal from beingfalsified in the event of interference. The conductors can have aninsulation, preferably additional insulation, which has a higher meltingpoint than the pipe. The same is true for the covering SR4 enclosingsaid conductors. This can be achieved, for example, by crosslinking theinsulating material. This makes it possible to achieve better emergencyrunning properties. The electric conductors, for example EL31 and EL32,can be used as fire detectors, the distance to the location of the firebeing measured directly, for example by means of a pulse reflection, byan appropriate monitoring device (for example AE in FIG. 1 and, inparticular, in large buildings). To this end, pulses are fedcontinuously into at least one of the conductors EL31 and/or EL32, andtheir propagation time is measured. If a change occurs, because theconductor carrying the measuring pulses, for example EL31, is destroyedor damaged, for example as a result of a fire, then the echo propagationtime changes. This can be used to detect a fire.

A measurement of electrical properties, for example of insulation and/orresistance changes in the case of at least one of the conductors EL31and/or EL32 as a result of a local increase in temperature can also becarried out (for example by the alarm and monitoring device AE in FIG.1). Even before a fire breaks out, a change in the electrical propertiesof the adjacent conductors in the extinguishing-line system RO31 mayoccur in this way, for example as a result of local overheating whichhas possibly not yet led to a fire. These changes can be registered at acentral monitoring point and countermeasures can then be initiated.

What is claimed is:
 1. A device for fighting fire in at least one cableor line run containing a cable and/or a line, said device having atleast one pipe, which contains a fire-extinguishing agent under positivepressure, being laid continuously in the cable or line run, the wall ofsaid pipe being produced from a material whose melting point is chosento be equal to or lower than an ignition point of the cable sheath or ofthe line, the improvement comprising the pipe being fitted with a watervapor barrier.
 2. A device according to claim 1, wherein the pipe isassigned at least one storage container for the fire-extinguishingagent.
 3. A device according to claim 2, wherein the device is installedin a building and has a plurality of storage containers provided atdifferent heights.
 4. A device according to claim 1, which includes apressure sensor connected to the pipe, so that with a pressure drop, thesensor outputs a signal for a fire alarm.
 5. A device according to claim1, which includes a pressure pump which, in the event of a pressuredrop, continues to maintain the pressure in the pipe.
 6. A deviceaccording to claim 1, wherein the pipe is produced of a materialselected from a group consisting of a polyethylene, a copolymer and acombination of a polyethylene and a copolymer.
 7. A device according toclaim 1, wherein the water vapor barrier is selected from a groupconsisting of a metal foil, a plastic film and a combination of a metalfoil and a plastic film.
 8. A device according to claim 1, wherein thewater vapor barrier is fitted to the inside of the pipe.
 9. A deviceaccording to claim 1, wherein the water vapor barrier is fitted to theoutside of the pipe.
 10. A device according to claim 1, wherein thewater vapor barrier is embedded in the wall of the pipe.
 11. A deviceaccording to claim 1, which includes an alarm device, the pipe beingprovided with at least one metallic conductive wire provided with anelectrical voltage so that with an outbreak of a fire, a change in theelectrical properties in the wire triggers a signal in the alarm device.12. A device according to claim 1, which includes a signal generator andat least who mutually insulated conductors being equipped on the pipeconnected to the signal generator.
 13. A device according to claim 12,wherein the conductors are surrounded by a shield against interferencewhich has a higher melting point than the pipe.
 14. A device accordingto claim 12, wherein the conductors are surrounded by an insulationhaving a higher melting point than the pipe.
 15. A device according toclaim 1, which is arranged in a vehicle.
 16. A device for fighting firein a cable run in a compartment, said device having at least one pipecontinuously present in the cable run, and means for maintaining afire-extinguishing agent under positive pressure in the pipe, said pipebeing made of a material having a melting point ≦ a lowest ignitionpoint of any material of the cable in the run and said pipe having awater vapor barrier.